Early fetal anatomy screening

PURPOSE OF REVIEW: This article reviews the potential benefits and downsides of early anatomy screening. RECENT FINDINGS: There is increasing evidence that about 50% of severe fetal anomalies can be diagnosed prior to 14 weeks of gestation. 'Red flags' such as an increased nuchal or intracranial translucency, tricuspid valve regurgitation, a small biparietal diameter, a single umbilical artery or an abnormal retronasal triangle should raise the sonographer's suspicion of a congenital defect and warrant a more thorough fetal assessment, which often includes transvaginal scanning. Care should, however, be taken not to overinterpret first-trimester findings as false-positive rates of 3-4% have been reported. With more subtle findings, and especially if a heart defect is suspected, a sonographic reassessment after 15 weeks' gestation is indicated. Patients should be counseled that findings could worsen but also improve with time. SUMMARY: Basic fetal anomaly screening should be recommended, piggybacked on the routine first-trimester (aneuploidy screening) ultrasound, both for low and high-risk populations. First-trimester anatomy screening seems particularly useful in obese women, whose fetuses are difficult to screen at the midtrimester ultrasound and in multiple gestation. Noninvasive prenatal testing using cell-free fetal DNA can complement but should not replace first-trimester ultrasound.